Core taker devices



Nov. 30, 1965 Filed Nov. 12, 1963 H. J. URBANOSKY ETAL CORE TAKER DEVICES 2 Sheets-Sheet l ATTORNEY Nov 30 1965 URBANOSKY ETAL 3,220,490

CORE TAKER DEVICES 2 Sheets-s 2 Filed Nov. 12, 1963 INVENTORS Haifa/d /bO'NOJAy fmmez f. 5 /899/ United States Patent f 3,220,490 CORE TAKER DEVICES Harold J. Urbanoslry, Houston, and Emmet F. Brieger,

Needville, Tern, assignors to Sehlumherger Well Surveying Corporation, Houston, Tex, a corporation of Texas Filed Nov. 12, 1963, Ser. No, 322,822 12 Claims. (Cl. 1754) This invention relates to apparatus for obtaining solid samples of earth formations and, more particularly, pertains to a new and improved core-taking apparatus for obtaining a solid sample of earth formation material.

Generally, cores or samples of earth formation material are obtained by lowering a side wall sample taker assembly into the borehole to the level of the formation to be investigated. The sample taker assembly includes a gun body which receives a number of hollow core-taking bullets together with explosive means which are selectively operable so that the bullets may be impelled toward and into a formation, with the hollow interior of the bullets thereby receiving the formation material. Usually, the core bullet is secured to the gun body by one or more flexible retrieving connections so that a pull, as by raising the gun body, serves to withdraw the core bullet with a formation sample from the earth formations. Thus, a formation core sample can be retrieved to the surface of the earth for examination and testing.

However, many problems are presented by the variety of formations which are encountered in sampling operations. For example, the types of formations may be generally classified as (1) soft, (2) medium, (3) firm, (4) hard, and (5) extra hard. Thus, the problems may vary from the difficulty in getting the bullet into the extra hard formations without damage to the diificulty encountered in soft formations in the withdrawal of the core bullet from the formation. To obtain core samples from the various types of formations, different types of core bullets have been designed to meet the various conditions arising. Aside from the problem of retrieving the core bullets, it is, of course, necessary to obtain a core sample which is representative of the formation tested.

Particularly in the soft to firm formations, recovery of core bullets has been facilitated by providing the core bullet with a separable forward portion in the form of an annular cutting ring which generally has a slightly greater outer diameter than the core barrel. Thus, the ring forms an enlarged hole relative to the body of the bullet to alleviate sticking of the bullet body in the formation. When a pull is exerted on the body of the bullet, it should separate from the cutting ring thereby to leave the cutting ring in the formation. Various cutting ring attachments have heretofore been used such as the types disclosed in Patents No. 2,923,530, No. 3,101,- 797 or No. 3,072,202.

It has been found in many instances that the core bullet becomes so firmly embedded that in pulling on the bullet in the formations, the wire-retrieving connections are broken.

Accordingly, it is an object of the present invention to provide new and improved core-taking apparatus for minimizing the retrieval pull required on a core-taking bullet.

Another object of the present invention is to provide new and improved core-taking apparatus which is selfretracting from earth formations.

Still another object of the present invention is to provide new and improved core-taking apparatus which is hydraulically self-retracting from earth formations.

In apparatus for obtaining a core sample, in accordance with the present invention, a gun body receives 3,229,499 Patented Nov. 30, 1965 one or more core-sampling bullets which may be disposed lengthwise of the gun body. The bullet is adapted to be impelled toward and into earth formations by explosive means and has a body member with a cutting ring member releasably received on its forward end. Means are provided to operate after the bullet has left a gun body and is in the earth formations to move the body member rearwardly relative to the ring member. Thus, the body member is retractable from earth formations relative to the ring member independent of the usual retrieving wire members.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a view in partial cross-section of apparatus embodying the present invention for obtaining a core sample and illustrated in a well bore;

FIG. 2 is a view in cross-section of a bullet embodying the present invention;

FIG. 3 is a view in cross-section of a bullet embodying another form of the present invention;

FIG. 3A is a partial view of a modification of the bullet of FIG. 3; and

FIGS. 4-6 are views in cross-section of bullets embodying other forms of the present invention.

In FIG. 1 of the drawings, there is shown a gun block or body 10 disposed in a borehole 11 opposite a formation 12 of interest. Usually, borehole 11 contains a drilling rnud 13.

Gun block 10 has a cylindrical bore 14 adjoining a bore 15 of smaller diameter, the bore 15 forming a powder chamber which terminates short of the rear surface 16 of the gun block. Chamber 15 contains an appropriate and conventional explosive propellant 17 while bore 14 receives a generally cylindrical core-taking device or bullet assembly 18 constructed in accordance with the present invention. Although not illustrated, gun block 10 generally contains additional bullet assemblies in respective bores distributed along a vertical axis for the gun block.

Bullet assembly or bullet 18, near its rearward end, has spaced annular grooves which receive O-rings 19, 19a to provide a fluid-tight seal for the bullet assembly 18 in the bore 14, and flexible retrieving wires 20 are secured in a conventional manner between the bullet assembly and gun block 10 to permit the bullet body of the assembly to be retrieved. A conventional igniter 21 suitably mounted in the block 10 may be employed to detonate the explosive propellant 17 and thereby propel the bullet 18 toward and into the formation.

Referring now to FIG. 2, bullet or bullet body member 18 is comprised of three parts, to wit, a forward tubular sample-receiving core part 21, an intermediate coupling part 22 and a rearward bottom part 23. Forward part 21 has a forwardly facing shoulder 24 which releasably receives a cutting ring or release member 25 and a snap ring 26 is provided to insure retention of ring 25 on the shoulder 24 of part 21. Ring member 25 has the usual, conically shaped forward surface and is disposed slightly rearwardly of the forward cutting edge 27 on the tubular part 21. Ring member 25 is also slightly greater in overall diameter than the diameter of the body portion rear- Wardly of the cutting ring member to reduce the area of the bullet in the formation subject to hydrostatic pres sure. The purpose of the cutting ring member 25 is to provide an oversized hole so that the outer body of the bullet 18 is prevented from intimate contact with the earth formations, the ring member being left embedded in the earth formations. Of course, the precise connection and arrangement of the ring member relative to the bullet body is immaterial to the present invention so long as the ring member when in the earth formations is releasable from the bullet body. ring arrangement, however, is preferable since the forward end of member 21 extends beyond ring 25 and obtains a better core sample more reliably.

Tubular core part 21 also has ports 28 in its side walls and connections 29 for attachment of retrieving wire elements 20 to the bullet body.

Coupling part 22 of bullet 18 provides a bottom 30 for the tubular core part 21 and has a rearward threaded bore 31 receiving a threaded stud 32 on bottom part 23. Bottom part 23 has a flanged portion 33 forming a piston which is slidably and sealingly received in gun bore 14 by means of the O-ring 19. Intermediate of flanged portion 33 and intermediate coupling part 22, a portion of the bottom member 23 is reduced in diameter at 22a to slidably and sealingly receive a piston portion 34 of selfreleasing sleeve 35. Sleeve 35 has a groove receiving the O-ring 19a so that the sleeve 35 is sealed in bore 14 while an O-ring 36 provides a seal between piston portion 34 on bottom portion 22a. An O-ring 37 is provided on the intermediate part 22 to seal this part relative to sleeve 35. A chamber 38 is formed between sleeve 35 and parts 22, 23 and is pressure sealed by the O-rings 36, 37. Sleeve 35 has a forward end suitably slotted to accommodate connections 29 and an end surface 39 which is adjacent to the cutting ring member 25.

In operation, when the powder 17 is ignited, the bullet is accelerated from bore 14 toward and into adjacent earth formations. Snap ring 26 is displaced from its groove leaving the cutting ring 25 free, the cutting ring staying on the bullet body due to the forward movement of the bullet body. As the forward end of the bullet penetrates the formation, the cutting ring 25 makes a large hole and keeps the portion of the bullet and sleeve 35 rearwardly of the ring from intimate contact with the formation.

When O-ring 19a clears the bore 14, hydrostatic pressure acts on the piston portion 34 of sleeve 35, the coupling part 22 and the bottom part 23 in a manner to reduce the volume of chamber 38. As chamber 38 is closed, end surface 39 of the sleeve 35 is forced against the release ring 25. The force pushing the sleeve 35 is equal to the area bounded by seals 36, 37 times the hydrostatic pressure. There is an equal and opposite force acting on part 22 which pulls the body member with a formation core out of the formation and through the release ring. This retracting operation takes place when the bullet is in the formation and the entire assembly with core, but less snap ring 26 and release ring 25, is subsequently returned with the retrieving wires 20 to the surface. While FIG. 2 discloses the basic principles of the present invention, the preferred embodiment of this inention is disclosed in FIG. 3.

The apparatus of FIG. 3 is essentially the same as the apparatus of FIG. 2 except that a dump chamber 46 is formed within the parts 22 and 23 and an orifice 41 provided between the chamber 38 and dump chamber 40. Chamber 38 is filled with a relatively non-compressible fluid such as water, oil, grease, jelly or a semi-solid such as soap or wax. This fluid in the chamber 38 will then be displaced through the orifice 41 into the dump chamber (which is initially at atmospheric pressure) at a relatively slow rate and provide a time delay insuring that the bullet enters the formation before the retracting function is performed. Rather than specifically form a dump chamber 40 in the parts 22, 23, it will be appreciated that in the device of FIG. 2, the clearance space between parts 22 and 23 and the stud 32 in threaded bore can be provided with sufficient clearance to form flow-restrict- .ing means and a dump chamber. Moreover, as shown The above-described in FIG. 3A, the chamber 33 can be provided with an annular ring member 42 which is porous and permeable and occupies but a part of the chamber 38 with the remainder of the chamber 38 containing a relatively noncornpressible fluid. Thus, in operation of the variation of FIG. 3A, the fluid would be displaced into the porous permeable member 42 at a controllable rate.

Referring now to FIG. 4, another embodiment of the present invention is illustrated, the wire-retrieving connections 28 and flow ports 28 being omitted for clarity purposes. In this embodiment, the bullet body 18 is provided with a cylinder 43 receiving a piston 44 and associated rod member 45, the rod member being arranged to bear upon the cutting ring 25. The cylinder 43, behind the piston 44 in the body, opens to a restricted orifice and chamber portion 46 which, in turn, opens to a chamber 47 containing relatively non-compressible fluid. At the bottom of chamber 47 is a piston 48 and below the piston 48, chamber 47 opens to the exterior 59 of the bullet body. O-ring seals 51, 52 are provided above and below the exterior passageway opening and are disposed within bore 14.

In a manner of operation similar to that described heretofore, after the seal exits from bore 14, the hydrostatic pressure can act upon the fluid in the chamber 47 and displace the piston 44 and associated rod 45 to produce the self-retracting action of the bullet body.

Referring now to FIG. 5, still another embodiment of the present invention is illustrated, the wire-retrieving connections 20 and flow ports 28 being omitted for purposes of clarity. In FIG. 5, a bullet body 18" has a sleeve 35a slidably mounted thereon with an end portion 390 in engagement with ring 25. Body 18 has portions 54, 55, 56, respectively, and relatively having a smaller, a larger and an intermediate diameter. Sleeve 35a has a channel cross-section with portions 57, 58, 59, respectively, received by body portions 54-56. O-ring seals 60, 61, 62 are respectively provided between the sleeve and body portions. An annular recess 63 is formed be tween the sleeve and body permitting relative motion therebetween. The body between portions 54 and has a passageway 64 extending between the interior of sleeve 35:: between seals 69, 61 and a chamber 65 containing a relatively non-compressible fluid. The lower end of chamber is opened to the exterior of the bullet body by a passageway 66 and a piston 67 separates the passageway 66 from the fluid in chamber 65. O-ring seals 68, 69 are disposed above and below the exterior passageway opening to seal off the passageway 66 while in the bore 14.

When the powder 17 is ignited, the bullet 18 accelerates out of the bore 14 of block. 10. A seal 68 clears the mouth of the bore 14, hydrostatic pressure acts through passageway 66 on piston 67. Piston 67 forces the fluid in chamber 65 through orifice 64 at a controlled rate. After the bullet has penetrated the formation and all voids between orifice 64 and sleeve 35a are full, the bullet pulls itself from the formation. Thi is accomplished as follows: hydrostatic pressure acting on the top end of the sleeve 35a and over the area bounded by seals 60, 61 is balanced by fluid in chamber 65 acting underneath the sleeve and over the same area; forces due to hydrostatic pressure acting on each end of the sleeve and over the area bounded by seal 61 and the outer diameter of the sleeve are balanced; this leaves a force, due to hydrostatic pressure acting over the area bounded by seals 61- and 62, which moves sleeve 35a in a direction to diminish chamber or space 63 which is at atmospheric pressure; there is an equal and opposite force which pulls bullet body with a core out of the formation and through ring 25.

Referring now to FIG. 6, another embodiment of the present invention is illustrated, the wire-retrieving connections 26 and flow ports 28 being omitted for purposes of clarity. In this embodiment, a sleeve 35b has a flanged portion 70 disposed on the bullet body 18" between the ring member and a shoulder 71 and an O-ring seal 72 is provided. The tubular extension 71a of sleeve 35b is also sealed relative to the bullet body by an O-ring 73. A passageway 74 connects the space between seals 72, 73 with a chamber 75 containing a fluid. Chamber 75 opens to a larger cylinder 76 and a piston multiplier 77 with piston portions received in both chamber 75 and cylinder 76. A passageway 78 extends between cylinder 76 and the exterior of the bullet body and O-ring seals 79, 80 are provided to seal off the passageway opening Within bore 14. When the powder 17 is ignited, the bullet 18' accelerates out of the block. As seal 79 clears the bore 14, hydrostatic pressure act through passageway 78 on pressure multiplier 77. An atmospheric space 81 provided for the pressure multiplier 77 permits multiplier 77 to act on fluid in chamber 75 and such fluid is forced at a controlled rate, due to its passage through orifice 74, to fill all voids as the bullet penetrates the formation. The bullet then pulls itself from the formation in the following manner: hydrostatic pressure action on the top of sleeve 70 and over the area bounded by seals 72 and 73 is over-balanced by the pressure of the fluid under the sleeve and acting over the same area; this over-balance causes sleeve 70 to push against the bottom of ring 25; there is an equal and opposite force which pulls core bullet with a core out of the formation and through ring 25.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as' fall within the true spirit and scope of this invention.

What is claimed is:

1.- A formation core-taking device adapted to be fired from a gun body into earth formations about a well bore comprising: a tubular core-taking body member having a forward end, a formation-cutting ring member releasably received on said forward end, means operatively coupled between said body member and said ring member and responsive to pressure for providing a force on said ring member, and means for applying hydrostatic pressure between said pressure-responsive means and body member after said device is ejected from a gun body to urge said body member and said ring member in opposite directions when said ring member and a forward portion of said body member are embedded in earth formations so that said body member is moved relative to said ring member.

2. A formation core-taking device adapted to be fired from a gun body into earth formations about a well bore comprising: a tubular core-taking body member having a forward end, a formation-cutting ring member releasably received on said forward end, a normally expanded chamber in said device, means for contracting said chamber at a controlled rate upon exposure to fluids in a well bore after ejection from a gun body, and means connected between said ring member and body member, including a part functionally associated with contraction of said chamber for engaging said ring member upon contraction of said chamber permitting movement of said body member relative to said ring member.

3. A formation core-taking device including a portion adapted to be received in a gun body and fired therefrom into earth formations about a Well bore comprising: a tubular core-taking body member having a for- Ward end, a formation-cutting ring member releasably received on said forward end, means responsive to hydrostatic pressure for releasing said cutting ring member including a sleeve member slidably mounted on said body member and arranged for forward travel thereon upon firing of said device, said sleeve member having a rearward portion forming normally-expanded chamber means with said body member arranged to contract upon forward travel of said sleeve member and a forward por: tion for engagement with said ring member upon forward travel of said sleeve member, and means for retarding contraction of said chamber means at a controlled rate as said sleeve member travels forwardly.

4. A formation core-taking device adapted to be fired from a gun body into earth formation about a well bore and comprising: a tubular core-taking body member having a forward end, a formation-cutting ring member releasably coupled on said forward end, rigid means for contacting said ring member, hydraulic means for moving said body member relative to said rigid means including collapsible chamber means normally containing a fluid, means in said body member for receiving said fluid at a controlled rate.

5. A formation core-taking device adapted to be fired from a gun body into earth formations about a well bore and comprising: a tubular core-taking body memher having a forward end, a formation-cutting ring member releasably coupled on said forward end, rigid means for contacting said ring member, hydraulic means for moving said body member relative to said rigid means including collapsible chamber means normally containing a fluid, a dump chamber in said body member and orifice means coupling said chamber means to said dump chamber.

6. A formation core-taking device adapted to be fired from a gun body into earth formations about a well bore comprising: a tubular core-taking body member having a forward end, a formation-cutting ring member releasably received on said forward end, said device including a slidable member on said body member and pressureresponsive means for producing motion of said slidable member relative to said body member after leaving a gun body, said slidable member and body member having effective pressure areas for pressure biasing said body member rearwardly relative to said cutting ring member and moving said slidable member forwardly into engagement with said cutting ring member.

7. A formation core-taking device adapted to be fired from a gun body into earth formations about a well bore comprising: a tubular core-taking body member having a forward end, a formation-cutting ring member releasably received on said forward end, said device including a slidable member on said body body member and pressure-responsive means for producing motion of said slidable member relative to said body member after leaving a gun body, means for delaying such relative motion sufficient to insure embedding of said ring member and body member in earth formations, said slidable member and body member having effective pressure areas for pressure biasing said body member rearwardly relative to said cutting ring member and moving said slidable member forwardly into engagement with said cutting ring member.

8. Sample-taking apparatus comprising a body means with an open bore, a formation core-taking device received in said open bore and including a body member having a forward tubular core-taking portion, a formation-cutting ring member releasably received on said forward body portion, a sleeve member with a forward portion adapted to engage said ring member, said sleeve member being slidably mounted on said body member, hydraulic means in said device for moving said body member relative to said sleeve member in response to hydrostatic pressures in a well bore, a passageway connecting said hydraulic means to the exterior of said device for response to hydrostatic well pressures, and sealing means on said core taking device for sealing said passageway relative to said body means while said device is in said open bore.

9. A formation core-taking device adapted to be received in a gun body and fired therefrom into earth formations about a well bore comprising: a tubular coretaking body member having a forward end, a formationcutting ring member releasably received on said forward end, means responsive to hydrostatic pressure for releasing said cutting ring member including a sleeve member slidably mounted on said body member and arranged for forward travel thereon upon firing of said device, said sleeve member having a rearward portion adapted for Sliding reception in a gun body forming normally-expanded chamber means with said body member arranged to contract upon forward travel of said sleeve member and a forward position for engagement with said ring member upon forward travel of said sleeve member, means for retarding contraction of said chamber means at a controlled rate, and means on said rearward portion of said sleeve member adapted for cooperation with a gun body for preventing forward travel of said sleeve member until after said core-taking device has been fired from a gun body.

10. Sample-taking apparatus comprising a body means with an open bore, a formation core-taking device having a body member received in said open bore and a forward tubular core-taking portion, a formation-cutting ring member releasably received on said forward body portion, a slidable sleeve member with a rearward portion forming normally-expanded collapsible chamber means with said body member and a forward portion movable into engagement with said ring member, said body member having a dump chamber, means disposed between said dump chamber and chamber means for controlling the rate at which said chamber means collapses, and means on said rearward portion of said sleeve member coopera'ble with said body means for preventing forward movement of said sleeve member until said device is ejected from said body means.

11. Sample-taking apparatus comprising a body means with an open bore, a formation core-taking device rebody member and a forward portion movable into engagement with said ring member, said chamber means initially being filled with a relatively non-compressible fluid, said body member having a dump chamber at low pressure, flow-retarding means disposed between said dump chamber and chamber means for controlling the rate at which said fluid is displaced into said dump chamber, and means on said rearward portion of said sleeve member cooperable with said body means for preventing forward travel of said sleeve member until said device is fired from said body means.

12. Sample-taking apparatus comprising a body means with an open bore, a formation core-taking device having a body member with a rearward portion slidably and sealingly received in said open bore, an intermediate reduced portion, and a forward tubular core-taking portion, a formation-cutting ring member releasably received on said forward body portion, a sleeve member having a rearward portion slidably and sealingly received in said open bore, said rearward portion of said sleeve member being slidably and sealingly mounted around said reduced body portion and providing a telescoping connection with a normally-expanded collapsible chamber therebetween adapted to receive a relatively non-compressible fluid, said sleeve member having a forward portion sealingly engaged with said forward body portion and adapted to travel forwardly and engage said cutting ring member, a dump chamber in said body member, and flow-restricting means connecting said dump chamber to said collapsible chamber for retarding displacement of fluid into said dump chamber to delay forward travel of said sleeve member.

References Cited by the Examiner UNITED STATES PATENTS 2,775,427 12/1956 Leone 4 X 2,901,220 8/1959 Linn 175-4 X 2,923,530 2/1960 Fields 175-4 X 3,072,202 1/1963 Brieger 1754 3,101,797 8/1963 Brieger 1754 CHARLES E. OCONNELL, Primary Examiner. 

1. A FORMATION CORE-TAKING DEVICE ADAPTED TO BE FIRED FROM A GUN BODY INTO EARTH FORMATIONS ABOUT A WELL BORE COMPRISING: A TUBULAR CORE-TAKING BODY MEMBER HAVING A FORWARD END, A FORMATION-CUTTING RING MEMBER RELEASABLY RECEIVED ON SAID FORWARD END, MEANS OPERATIVELY COUPLED BETWEEN SAID BODY MEMBER AND SAID RING MEMBER AND RESPONSIVE TO PRESSURE FOR PROVIDING A FORCE ON SAID RING MEMBER, AND MEANS FOR APPLYING HYDROSTATIC PRESSURE BETWEEN SAID PRESSURE-RESPONSIVE MEANS AND BODY MEMBER AFTER SAID DEVICE IS EJECTED FROM A GUN BODY TO 